I'm demoing out a setup with two sites, but the only thing site 2 has is an Indexer. The only purpose of the second site's indexer is disaster recovery. The idea is that I want site 2 (IDX2) to have a copy of itself and site 1 (IDX1). However, I only want site 1 to have its own data and not a copy of site 2.
I've been playing around with site_replication_factor and the I think the secret lays in the origin, but I'm really having a hard time wrapping my head around it.
You can't do it with the search and replication factors.
The best solution is "don't forward any data to site2 indexers." Make sure your forwarders are only sending data to site1 indexers.
If you aren't forwarding any data to site2, it will not be the origin for any data - and so it won't have anything to replicate, regardless of the settings.